Cradled in the cargo bay of the shuttle Columbia stands a new orbiting observatory that could shed light on some of the most violent processes and darkest mysteries the universe holds.

Using the unique capabilities of the Chandra X-Ray Observatory, astronomers hope to map the distribution of dark matter, peer to the edge of black holes, and answer the mystery of the age of the universe.

Astronomers worldwide have flooded officials with requests for observing time on the new telescope, which the Columbia crew will place into orbit sometime after the space shuttle launch next Tuesday.

The first round of observing opportunities drew 800 proposals, of which 200 were approved, says Harvey Tananbaum of the Chandra X-Ray Observatory Center in Cambridge, Mass. "We were oversubscribed by four or five to one," he says.

Dark matter comes to light

Much of the enthusiasm stems from the new light Chandra is expected to shed on the mysterious existence of "dark matter," the mass in the universe which is undetectable except by its gravitational effects.

All matter has gravity, and this attractional pull holds the universe together. Since observable matter does not come close to accounting for all the gravitational effects astronomers observe, scientists have long postulated the existence of dark matter to account for the discrepancy. In fact, it is estimated that 90 percent of the mass of the universe is dark matter. Some explanations for this hidden mass have involved black holes, cosmic strings, and various exotic particles such as weakly interacting massive particles (WIMPS).

Scientists are especially excited to take a look at A1367, a cluster of galaxies 300 million light-years from Earth. Imaged through an optical telescope, the cluster appears as small white blotches sprinkled against the blackness of space. Viewed through an X-ray telescope, however, the cluster is cloaked in gas clouds millions of light-years across and reaching temperatures as high as 40 million degrees. The gas contains more mass that all the stars in all the galaxies in the cluster.

Typically, such a cloud of hot gas might be expected to expand and thin over time. But clusters of different ages show similar, stable formations of gas. Physicists suggest that gravity from dark matter keeps the clouds in check.

Astronomers will use Chandra to map the clouds in A1367 and other galaxy clusters, providing new insights into how dark matter may be distributed. The telescope's ability to distinguish fine features in the clouds could yield clues about the nature of the dark matter corralling them.

Black hole's horizon

Chandra also will allow astronomers to peer closer than ever to the "event horizon" of black holes, where matter is so massive and dense that their gravity prevents even light from escaping. The event horizon is the brink beyond which matter appears to vanish. As it swirls into the maw, inflowing material generates enormous amounts of X-rays, which bear clues about the processes occurring as the material disappears from view.

"The X-ray observatory will allow astronomers unprecedented views of some of the most extreme conditions in the universe ... and it will test the laws of physics under conditions impossible to duplicate on the earth," says Ed Weiler, an administrator of NASA's Office of Space Science.

The key to Chandra's potential lies in its ability to distinguish between closely spaced objects from a great distance, according to Martin Weisskopf, Chandra project scientist at the Marshall Space Flight Center in Huntsville, Ala. "With Chandra's optics, you could read a newspaper a half a mile away," he says. "The nested mirrors are so smooth, that if they were the size of Colorado, the highest feature would be an inch tall."

A new step forward

Tipping the scale at just over 5 tons and stretching 45 feet from end to end, Chandra is the largest satellite a shuttle has ever launched. A high-resolution camera will image objects, while a powerful spectrometer will help researchers determine the chemical composition of physical processes affecting the objects they study.

Project participants say the craft represents a significant step forward in a field of research that is less then 40 years old. With Chandra, X-ray telescopes will have achieved in 20 years the same ability to resolve distant objects that optical telescopes took more than 300 years to attain.

Most revolutions in science arise from improvements in observing tools, according to Martin Elvis of the Harvard-Smithsonian Center for Astrophysics.

As if to underscore the point, NASA's Dr. Weiler says, "Some of the most important and exciting results will not involve the questions astronomers currently plan to seek Chandra's help in answering. They will be discoveries of the unexpected."